Breed Of Dam Research Articles

Samae Dam chicken: a variety of the Pradu Hang Dam breed revealed from microsatellite genotyping data.

The remarkable adaptability to the environment, high growth rate, meat with good taste and aroma, and ornamental appearance of the Pradu Hang Dam (PDH) and Samae Dam (SD) chickens make them valuable for improvement of poultry production to enhance food security. However, despite their close phenotypic similarity, distinct classification of PDH and SD chickens remains controversial. Thus, this study aimed to clarify genetic origins and variation between PDH and SD chickens, genetic diversity and structures of PDH and SD chickens. This study analyzed 5 populations of PDH and 2 populations of SD chickens using 28 microsatellite markers and compared with those of other indigenous and local chicken breeds using Thailand's "The Siam Chicken Bioresource Project" database. Considerably high genetic variability was observed within PDH (370 total alleles; 4.086±0.312 alleles/locus) and SD chickens (179 total alleles; 3.607±0.349 alleles/locus). A partial overlap of gene pools was observed between SD chickens from the Department of Livestock, Uthai Thani (SD1) and PDH chickens, suggesting a potentially close relationship between the two chicken breeds. A gene pool that partially overlapped with that of the red junglefowl was observed in the SD chicken population from the Sanhawat Farm Uthai Thani population (SD2). Distinct subclusters were observed within SD chickens, indicating the possibility that genetic differentiation occurred early in the process of establishment of SD chickens. These findings could offer valuable insights into genetic verification of Thai local chicken breeds and their sustainable conservation and utilization.

Comparative analysis of reproductive tract microbiomes in modern and slower-growing broiler breeder lines.

The reproductive tract microbiome in hens is of interest because bacteria in the reproductive tract could potentially affect fertilization and egg production, as well as integrate into the forming egg and vertically transmit to progeny. The reproductive tract microbiome of 37-week-old modern commercial Cobb breeding dams was compared with that of dams from a broiler Legacy line which has not undergone selection since 1986. All animals were kept together under the same management protocol from day of hatch to avoid confounders. In regards to reproductive abilities, Cobb dams' eggs weighed more and the magnum section of their reproductive tract was longer. In regards to microbiome composition, it was found that the reproductive tract microbiomes of the two lines had a lot in common but also that the two breeds have unique reproductive tract microbiomes. Specifically, the order Pseudomonadales was higher in the magnum of Legacy dams, while Verrucomicrobiales was lower. In the infundibulum, Lactobacillales were higher in the Legacy dams while Verrucomicrobiales, Bacteroidales, RF32 and YS2 were lower. our results show that breeding programs have modified not only the physiology of the reproductive tract but also the reproductive tract microbiome. Additional research is required to understand the implications of these changes in the reproductive tract microbiome on the chicken host.

Sire breed has a larger impact on sensory and technological meat quality than dam breed in beef-on-dairy heifers reared on forage and semi-natural grasslands

The aim of this study was to evaluate the meat quality of beef-on-dairy heifers from Holstein or Swedish Red-and-White dams sired by Angus or Charolais bulls reared on forage and semi-natural grasslands. Production systems with moderately high and low feeding intensities were compared, where animals grazed for one or two summers and were slaughtered at 20 or 27 months of age, respectively. Meat quality of crossbred heifers from Holstein and Swedish Red-and-White dams was comparable in M. longissimus lumborum (LL) and differed in pH, yellowness and Warner-Bratzler shear force (WBSF) in M. semimembranosus (SM) with Swedish Red-and-White being less tough. Compared with LL from Charolais crossbreeds, LL from Angus was redder and had lower WBSF, higher intramuscular fat concentration (IMF%), a more pronounced metallic flavour and a more pronounced umami taste. Meat quality of SM did not differ between Angus and Charolais crossbreeds. Generally, the production system with moderately high feeding intensity resulted in less tough beef that was lighter and less red and had higher IMF%. Consequently, beef from Charolais crossbreeds reared at a low feeding intensity exhibited the poorest meat quality with the lowest IMF% in LL (2.80 and 3.77 % for Holstein and Swedish Red-and-White, respectively). Nevertheless, crossbreeds did not differ in sensory meat quality. Generally, meat quality of beef-on-dairy heifers reared on forage and semi-natural grasslands was high, and while Angus crossbreeds delivered high-quality beef from both feeding intensities, Charolais crossbreeds are better suited for the moderately high feeding intensity, when aiming for high meat quality.

The links between positive human interaction and maternal behaviour and welfare of commercial breeding dams (Canis familiaris)

In dogs, maternal behaviour plays an essential role in offspring survival and can influence the development and behaviour of the neonate later in life. We investigated the effect of prepartum enrichment on maternal behaviour and welfare of breeding dams at a large-scale commercial dog breeding establishment. During the last four weeks of gestation, dams were exposed to either baseline management conditions (control N = 13) or an additional enrichment protocol based on positive human interaction (enriched N = 13). We then recorded the duration of mother-puppy interactions throughout the first three weeks postpartum. Hair samples for cortisol analysis were collected at four timepoints: 3rd week of gestation, last week of gestation, 4th week postpartum, and 8th week postpartum. Additionally, the behaviour of the dams was assessed during the 3rd week of gestation. We hypothesised that, compared to control dams, enriched mothers would show higher levels of maternal behaviour and lower post-treatment and post-partum levels of hair cortisol. With the exception of vertical nursing, all the recorded maternal behaviour variables declined over time. None of the maternal behaviour variables were significantly affected by the enrichment treatment. However, as litter size increased, enriched dams spent marginally more time nursing their puppies in a sitting or standing posture (vertical nursing). Similarly, as litter size increased, enriched dams had significantly lower average hair cortisol concentration (HCC) levels compared to dams in the control group. Furthermore, dams scoring higher in the pre-treatment behavioural assessment (being more social towards humans and other dogs, less fearful and reactive, and more willing to play and interact with unfamiliar stimuli) had lower HCC levels. HCC did not vary significantly across the four timepoints. Overall, these findings suggest that although higher HCC levels in dams bearing larger litters could be associated with elevated energy mobilisation during pregnancy and lactation, a potential stress-mitigating effect of the positive human interaction cannot be excluded. Further studies should investigate this potential stress-mitigating effect using additional welfare indicators.

Effects of Dam and Sire Breeds on Lamb Carcass Quality and Composition in Pasture-Based Systems.

This study explored the impacts of sire and dam breed on carcass quality and composition in a pasture-based system and the use of DXA to rapidly rank carcasses for leanness. Southdown (SD) and Suffolk (SF) ewes were mated to Texel (TX) or SD rams to produce seventy-nine lambs. Lambs were raised on pasture-based systems with limited grain supplementation. Lamb birth weight was greater (p < 0.01) for TX, regardless of dam breed. Lambing rate was lower (p < 0.01) for SD than SF ewes. Circulating myostatin concentrations were greater (p < 0.05) on d 42 than d 75 or d 110 but did not differ by sire breed. Texel-sired lambs had greater (p < 0.01) carcass weight, ribeye area and quality grade compared to SD-sired. Total and primal fat mass as predicted from DXA was higher (p < 0.05) in carcasses from SD than TX sires. Muscles from TX lambs had greater (p < 0.05) polyunsaturated fatty acid (PUFA) composition than SD-sired. Shear force values were influenced (p < 0.01) by dam breed, muscle cut and postmortem age but not by sire breed. The use of TX sires in pasture-based systems improved carcass leanness and muscle PUFA concentrations without altering tenderness.

An Assessment of the Genetic Parameters of Boars' Reproductive Traits.

The aim of this study was to estimate genetic parameters for the reproductive traits of boars based on single-nucleotide polymorphism data. A total of 109,836 semen samples from 2249 boars were collected between 2010 and 2022. Five basic traits were assessed: sperm volume, sperm concentration, motility, number of abnormal sperm, and, for the first time for the local population, libido. In addition, two derived traits were assessed: total sperm count and number of functional sperm. Genetic parameters were estimated using the single-step genomic best linear unbiased prediction method (ssGBLUP). Dam and sire breeds were evaluated separately. The five basic traits were evaluated using five-trait models, while the two derived traits were evaluated using single-trait models. The heritability coefficients had lower values for all sperm quality traits with both methods. For the basic traits, the heritability ranged from 0.099 to 0.342. The greatest difference between dam and sire breeds was observed for the heritability of the sperm concentration trait (0.099 and 0.271, respectively). The heritability of the libido trait was twice as high for boars of sire breeds as it was for boars of dam breeds. The genetic parameters estimated with ssGBLUP can be used in routine genetic evaluations to improve the pig breeding process.

Reproductive performance of Horro and Horro-crossbred dairy cows in Ethiopia's subhumid tropical environments.

Estrus detection, timing of insemination, feeding, and health care practices are all factors that can significantly affect cattle breeding efficiency and lifetime production. In Ethiopia's subhumid environment, the age at first calving, number of days open, duration from calving to first heat, and number of services per conception are economic traits that affect reproductive performance of Horro and Horro-crossbred dairy cows. Data collected at Ethiopia's Bako Agricultural Research Center between 1980-2019 was used to study the reproductive performance of Horro and Horro-crosses with Holstein Friesian and Jersey dairy cows. We identified overall mean ± standard error values of factors that affect reproductive performance, including age at first service (AFS) (29.2 ± 0.2 months), age at first calving (AFC) (39.8 ± 0.2 months), number of services per conception (NSC) (1.76 ± 0.4 months), calving interval (CI) (13.2 ± 0.3 months), days open (DO) (94.3 ± 4.3 days), conception rate (CR) (75.0 ± 1.3%), and replacement rate (RR) (28.4 ± 0.3%). The odds ratios of the 60-day and 90-day nonreturn rates (NRR) were 0.22 and 0.96, respectively. Sire and dam breed and birth period had significant (P < 0.001) effects on AFS and AFC, while season and dam parity had significant effects on CI and DO. Inconsistencies regarding feeding, heat detection, inseminator skills, insemination timing, animal health, and other husbandry practices may extend periods of AFS, AFC, CI, and DO. To optimize reproductive performance in Horro cows and Horro crossbreeds in Ethiopia's subhumid environments, improving management practices should be a priority.

Does the climate influence the variance of residual in litter traits of Taiwan Landrace sows?

Heat stress adversely affects the litter traits of Landrace, the primary dam breed in Taiwan. This study aimed to evaluate the effects of heat stress during sow pregnancy with homogeneous and heterogeneous residuals to estimate the genetic parameters of the Taiwan Landrace. Performance records for 11 657 litters and weather data from 2008 to 2021 were collected. The climate effect was defined proportionally from cool to hot for climates 1 to 5. The homogeneous residual analysis showed that the heritabilities of the total number born (TNB) and number born alive (NBA) were 0.164 ± 0.014 and 0.111 ± 0.014 with residual variances of 10.338 and 9.164, respectively. The heterogeneous residual analysis showed that the residual variances for TNB and NBA were 8.934–11.113 and 8.196–9.810, respectively. For TNB, the residual variance in the herd–year–climate effect differed significantly in climate 1 from climates 3 to 5 ( p &lt; 0.01). In NBA, the residual variance was significantly lower in climates 1 and 2 than in climates 3 and 5 ( p &lt; 0.01). In conclusion, heritability was estimated for TNB and NBA. In addition, residual variances could interact with the climate effect in heterogeneous residual analysis.

Discriminant Analysis Approach in Morphometric Differentiation and Characterization of Serbian Autochthonous Goats.

This study investigated the possibility of using morphometric measurements to differentiate the autochthonous Serbian White goat breed from Saanen and Balkan goats, which were used as sire and dam breeds in its creation. For this purpose, a multivariate discriminant analysis was used. A total of 11 morphometric traits were measured in 98 does of 3 breeds: Saanen (n = 28), Balkan (n = 28), and Serbian White (n = 42), aged 2 to 7 years, in 4 different locations. Univariate analysis of variance revealed a significant difference in body measurements of all three breeds, with Saanen goat being the largest in format and Balkan the smallest. Discriminant analysis extracted six out of eleven tested morphometric traits with the strongest discriminatory power: heart girth, head length, chest depth, head width, pelvic width, and body length. Mahalanobis distances were significant between all three genetic groups. The discriminant function correctly classified 95.24% of the Domestic White goats investigated to their source group. The classification accuracy of the function was cross-validated and indicated an overall success rate of 91.84%. The results of this research showed that there was a clear separation between Serbian White, Saanen, and Balkan goats. The present findings could help a more rapid field assessment of Serbian White goats.

Positive human interaction improves welfare in commercial breeding dogs: Evidence from attention bias and human sociability tests

Intensive breeding practices found in large scale Commercial Breeding Establishments (CBEs) raise significant concerns about breeding dam welfare. Large-scale CBE dams spend most of their reproductive lives confined to kennels, with limited access to enriching experiences including positive human interaction. Long-term confinement can have detrimental effects on dog welfare, inducing negative affective states like anxiety and depressive-like behaviour, and leading to the development of behavioural problems such as fearfulness towards unfamiliar people. Evidence in humans and other animals shows that negative affective states increase the subject’s attention towards a threatening stimulus. We tested the impact of positive human interaction on the welfare of breeding dams from a licensed UK CBE. After receiving four weeks of either baseline levels (control, N = 16) or additional positive human interaction (enriched, N = 15), an attention bias test (ABT) was conducted to assess dogs’ affective states. Afterwards, dams’ human sociability level was evaluated using a stranger approach test. Pre- and post-intervention hair cortisol samples were collected to determine the effect of enrichment on chronic stress. In the ABT, we predicted that, compared to enriched dams, control dams would look more frequently and for longer towards the position of a negative threatening stimulus (opening and closing umbrella) and would spend less time interacting with a positive rewarding stimulus (food bowl). In the stranger approach test, we expected enriched dams would score higher, suggesting more affiliative behaviour towards unfamiliar people. Results showed that control dams looked more frequently (p = 0.005) but not for longer (p = 0.148) towards the negative stimulus in the ABT. Moreover, enriched dams spent more time sniffing (p = 0.032) and eating (p = 0.005) from the food bowl. Additionally, enriched dams scored higher on average in the stranger approach test than dams in the control group (p = 0.026). No significant difference was observed in the percentage change of hair cortisol concentration between treatment groups (p = 0.135). To our knowledge, this is the first evidence for attention bias indicating affective state in dogs. This study demonstrates that a positive human interaction used as a form of enrichment can improve welfare and sociability towards strangers in commercial breeding female dogs. However, longer-term enrichment protocols may be needed to influence hair cortisol levels. Dams in large-scale breeding facilities would benefit from additional positive human interaction, particularly near the end of their reproductive life when they are rehomed as pets.

Differences in gut bacterial community composition between modern and slower-growing broiler breeder lines: Implications of growth selection on microbiome composition.

In the last century broiler chicken lines have undergone an extensive breeding regime aimed primarily at growth and high meat yield. It is not known if breeding has also resulted in a change to the broiler breeder's associated gut microbiota. Here we compared the gut microbiota of 37-week-old commercial Cobb breeding dams with dams from a broiler Legacy line which has not undergone selection since 1986. The dams from both lines were kept together in the same shed under the same management protocol from day of hatch to avoid additional confounders. We chose this age to allow significant bacterial exchange, thus avoiding exposure dependent artifacts and so that we could compare dams at the same developmental state of adulthood and peak laying performance. Significant differences in the composition of the cecum bacterial communities were found. Bacteria of the genus Akkermansia, implicated in mucin degradation and associated with host metabolic health, accounted for 4.98% ± 5.04% of the Cobb cecum community, but were mostly absent from the ceca of the Legacy line dams. Inversely, Legacy dams had higher levels of Clostridiales, Lactobacillales and Aeromonadales. These results show that breeding has resulted in a change in the gut microbiota composition, likely by changing the physiological conditions in the mucosa. It remains unclear if changes in gut microbiota composition are a part of the mechanism affecting growth or are a secondary result of other physiological changes accelerating growth. Therefore, the identification of these changes opens the door to further targeted research.

Beef embryos in dairy cows: calfhood growth of Angus-sired calves from Holstein, Jersey, and crossbred beef dams.

Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to characterize the effects of beef or dairy maternal genetics and the dairy management system on calf growth. Pregnancies were created with a 2 × 2 factorial arrangement of dam breed (Holstein or Jersey) and mating type (artificial insemination or implantation of an in vitro produced embryo from a commercial beef cow oocyte). Resulting calves were reared in a calf ranch. Additionally, commercial beef cows were inseminated and reared resulting calves on range. Therefore, the five treatments were Angus × Holstein (A × H; n = 19), Angus × Jersey (A × J; n = 22), Angus × beef gestated by Holstein (H ET; n = 18), Angus × beef gestated by Jersey (J ET; n = 8), and Angus × beef raised by beef (A × B; n = 20). Beginning at birth, calf body weight, cannon circumference, forearm circumference, top width, hip width, and hip height were measured approximately every 28 d until ~196 d of age. At birth, A × J calves weighed the least (P < 0.01). At 150 d of age, body weight was greatest (P < 0.05) among A × B calves, intermediate among H ET and A × H calves, and least among J ET and A × J calves (P < 0.05). Morphometric differences were detected between treatments (multivariate analysis of variance, P < 0.01). Primary discriminant function scores identified A × B calves having lesser values than A × J or A × H calves (analysis of variance [ANOVA], P < 0.01); A × B calves had greater cannon circumference, greater top width, and less hip height (standardized loadings of -0.47, -0.48, and 0.63, respectively). Secondary discriminant function scores identified J ET and H ET to have greater forearm circumference-a key indicator of muscling-than A × J or A × H (ANOVA, P < 0.01; standardized loading of 0.99). The dairy management system limited growth rate of beef genetics compared to the beef management system. In addition, Holstein dams transmitted greater growth potential than Jersey dams. Replacing maternal dairy genetics with beef genetics moderated frame size and created a more muscular phenotype.

Selection of dam breeds under stable and declined conditions

Reproductive selection index of two dam pig breeds was established five years ago to enhance the reproductive ability of sows. Since then, positive genetic progress in the population and some economic disorders (e.g. the input and output prices disproportion) appeared in the swine sector. The study aimed to revise index according to the current circumstances and further ensure the desired gain. In three index variants, the current, optimal, and adjusted trait proportion was assessed. Economic weights (EWs) of the breeding objective traits were applied in two alternatives to evaluate the index for future stable and deteriorated conditions. Under the current index construction and stable EWs, the favourable selection gain in piglets born alive (NBA) and slight extension of farrowing interval (FI) is indicated. The optimal index construction would result in a favourable gain of both traits in one breed. The adjusted index maintained the increasing litter size equal to the current index and achieved favourable gain in FI in both breeds. The same was true for deteriorated economic conditions except for the optimised index variant, where expected higher genetic progress in one breed. Nevertheless, this genetic gain was insufficient to compensate the declined EW of traits, and the overall financial benefit was almost half of those in stable conditions. For both alternatives of evaluated economic conditions, the current index should be revised in terms of a slightly higher proportion of FI to reach favourable genetic gain in both breeding goals.

PSIV-A-2 Beef Genetics in the Dairy Management System: Management System and Maternal Genetic Effects on Calf Growth and Body Measurements

Abstract Improved reproductive management allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to characterize effects of maternal genetics and the dairy management system on calf growth. Pregnancies were created with a 2 × 2 factorial arrangement of dam breed (Holstein or Jersey) and mating type (artificial insemination or implantation of an in vitro produced embryo from a commercial beef cow oocyte). Resulting calves were reared in a calf ranch. Additionally, commercial beef cows were inseminated and reared resulting calves on range. Therefore, the five treatments were Angus × Holstein (A×H; n = 19), Angus × Jersey (A×J; n = 22), Angus × Beef gestated by Holstein (H-ET; n = 18), Angus × Beef gestated by Jersey (J-ET; n = 8), and Angus × Beef raised by beef (A×B; n = 20). Beginning at birth, calf body weight, cannon circumference, forearm circumference, top width, hip width, and hip height were measured approximately every 28 days until approximately 196 days of age. At birth, A×J calves weighed the least (P &amp;lt; 0.01). At 150 days of age, body weight was greatest (P &amp;lt; 0.05) among A×B calves, intermediate among H-ET and A×H calves, and least among J-ET and A×J calves (P &amp;lt; 0.05). Morphometric differences were detected between treatments (MANOVA P &amp;lt; 0.01). Primary discriminant function scores identified A×B calves having lesser values than A×J or A×H calves (ANOVA P &amp;lt; 0.01); A×B calves had greater cannon circumference, greater top width, and less hip height (standardized loadings of -0.47, -0.48, and 0.63, respectively). The dairy management system limited growth rate of beef genetics compared to the beef management system. In addition, Holstein dams transmitted greater growth potential than Jersey dams. Replacing maternal dairy genetics with beef genetics increased top width and decreased hip height.

Breed and crossbreeding effects on growth, fitness and reproduction of commercial sheep in South Africa

The study aimed to assess additive breed effects for growth (birth, weaning and ewe adult weight), fitness (lamb survival and tick count under natural challenge) and ewe reproduction traits per ewe mated in Dorpers, the most common meat breed in South Africa (SA), and the SA Mutton Merino (SAMM) a prominent dual-purpose breed in SA extensive environments. Additionally, the reciprocal crosses between the two breeds were used to estimate dam breed effects and heterosis. No conclusive additive breed differences were found for lamb weight traits, lamb survival or tick counts. There was a suggestion that lamb survival of Dorpers was higher than that of their SAMM contemporaries, but significance could not be demonstrated. Crossbred progeny outperformed the midparent value by 7.1% for weaning weight. As far as mature ewes were concerned, mating weight was affected by breed combination with the mating weights of purebred SAMM ewes as well as crossbred ewes exceeding that of purebred Dorpers. Number of lambs born per ewe lambed was independent of the genetic group. The SAMM x Dorper group outperformed the pure breeds for number of lambs weaned per ewe mated (NLW). Contrasts for additive breed and maternal heterosis were not significant for NLW, but direct heterosis amounted to 32.5%. Crossbred ewes performed better than the pure breeds for total weight of lamb weaned per ewe lambed, direct heterosis amounting to 38.4%. The other contrasts were not significant. A lack of additive effects for traits, barring ewe mating weight suggested that the breeds performed similarly under the conditions of the study. Significant heterosis effects for weaning weight as well as number and weight of lamb weaned suggest a role for crosses between Dorpers and SAMMs in commercial lamb production enterprises.

Factors influencing ease of whelping and its relationship with maternal behaviour and puppy perinatal mortality in commercially bred dogs

For dog breeders, parturition is a critical stage in the reproductive cycle of the dam. Evidence in other mammals suggests that a difficult labour can influence maternal behaviour and offspring viability during the first hours postpartum. However, the effect of whelping difficulty on the onset of maternal behaviour has not yet been investigated in domestic dogs. Here we developed an ease of whelping (EoW) index in dams maintained within a Commercial dog Breeding Establishment (CBE) environment and investigated the relationship between intrinsic and extrinsic factors (breed group according to size/weight, litter size, parity, whelping season and origin of the dam), EoW, early maternal behaviour and puppy perinatal mortality. The behaviour of 30 dams was observed throughout the whelping process, starting 24 h before delivery of the first puppy until birth of the last puppy. Parturition duration, birth interval, and behaviours indicative of distress, restlessness, and general activity were scored and included in a Principal Component Analysis to construct the EoW index. Subsequently, mother–pup interactions and puppy perinatal mortality were recorded during the first 24 and 72 h postpartum respectively. Results showed that EoW was significantly affected by whelping season, litter size and origin of the dam (whether she was born and raised within the CBE or brought in). Furthermore, mothers that experienced more difficult parturitions (higher EoW score) spent more time lying in contact with their puppies during the first 24 h postpartum. Time in contact with puppies was also significantly affected by breed group. Nursing duration was significantly affected by breed group and origin of the dam. Additionally, medium-size breed (10–20 kg) puppies were significantly less likely to experience perinatal mortality than large breeds (> 20 kg). These findings are particularly relevant for the welfare of breeding dams maintained in large-scale CBEs where the staff-to-dog ratio might be insufficient to adequately manage multiple simultaneous parturitions.

Growth and Carcass Characteristics of Beef-Cross-Dairy-Breed Heifers and Steers Born to Different Dam Breeds

Simple SummaryThe dairy industry is an important source of animals for the beef industry in New Zealand. Since 1998, the proportion of Friesian–Jersey cows in dairy herds has increased from 19% to 49%. The aim of this study was to investigate the effect of dam breed on growth and carcass characteristics of beef-cross-dairy-breed progeny born to Friesian, Friesian-cross, Friesian–Jersey and Jersey-cross cows. Dam breed had an effect on all growth traits, as well as carcass weight, fat colour, fat depth, and ossification score. An increase in Jersey genetics in calves retained for beef finishing would result in calves that take a longer time to reach weaning weight and have a lighter carcass and yellower fat.Approximately two thirds of the annual beef kill in New Zealand originates from the dairy industry. The recent increase in Jersey genetics in the dairy herd will inevitably result in an increase in Jersey genetics entering the beef herd from retention of dairy-origin calves for finishing. Limited literature is available on the effect of dam breed on the performance of beef-cross-dairy-breed progeny. The aim of this study was to investigate the effect of dam breed from dams with varying proportions of Friesian and Jersey genetics on growth traits and carcass characteristics of their 24-month-old beef-cross-dairy-breed heifer and steer progeny. Liveweights of 142 heifers and 203 steers from Friesian (F), Friesian-cross (FX), Friesian–Jersey (FJ) and Jersey-cross (JX) dams were recorded at birth, weaning, as yearlings and at slaughter. Carcass characteristics were also recorded. At each point measured, liveweight was greatest for calves born to F dams. Calves born to F dams took 93 days to reach a weaning weight of 100 kg, whereas those from FX, FJ and JX dams took 99, 101 and 102 days, respectively. Carcass weight was greatest for progeny of F dams (286 kg, compared with 279, 275 and 276 for progeny of FX, FJ and JX dams, respectively). The progeny of JX dams had yellower fat than all other dam breed groups and a greater incidence of excessively yellow fat (fat score ≥ 5).

Influence of High Energy Diet and Polygenic Predisposition for Obesity on Postpartum Health in Rat Dams.

It is estimated that 30% of pregnant women worldwide are overweight or obese, leading to adverse health effects for both mother and child. Women with obesity during pregnancy are at higher risk for developing both metabolic and mental disorders, such as diabetes and depression. Numerous studies have used rodent models of maternal obesity to understand its consequences on the offspring, yet characterization of changes in the dams is rare, and most rodent models rely solely on a high fat diet to induce maternal obesity, without regarding genetic propensity for obesity. Here we present the influence of both peripartum high energy diet (HE) and obesity-proneness on maternal health using selectively bred diet-resistant (DR) and diet-induced obese (DIO) rat dams. Outbred Sprague-Dawley rats were challenged with HE diet prior to mating and bred according to their propensity to gain weight. The original outbred breeding dams (F0) were maintained on low-fat chow during pregnancy and lactation. By comparison, the F1 dams consuming HE diet during pregnancy and lactation displayed higher gestational body weight gain (P < 0.01), and HE diet caused increased meal size and reduced meal frequency (P < 0.001). Sensitivity to the hormone amylin was preserved during pregnancy, regardless of diet. After several rounds of selective breeding, DIO and DR dams from generation F3 were provided chow or HE during pregnancy and lactation and assessed for their postpartum physiology and behaviors. We observed strong diet and phenotype effects on gestational weight gain, with DIO-HE dams gaining 119% more weight than DR-chow (P < 0.001). A high-resolution analysis of maternal behaviors did not detect main effects of diet or phenotype, but a subset of DIO dams showed delayed nursing behavior (P < 0.05). In generation F6/F7 dams, effects on gestational weight gain persisted (P < 0.01), and we observed a main effect of phenotype during a sucrose preference test (P < 0.05), with DIO-chow dams showing lower sucrose preference than DR controls (P < 0.05). Both DIO and DR dams consuming HE diet had hepatic steatosis (P < 0.001) and exhibited reduced leptin sensitivity in the arcuate nucleus (P < 0.001). These data demonstrate that both diet and genetic obesity-proneness have consequences on maternal health.

PSXII-29 Evaluation of Barbados Blackbelly and St. Croix sheep under accelerated lambing using purebred and terminal sire mating: Lamb survival and body weight

Abstract Objectives were to evaluate lamb survival and body weight (BW) under an accelerated, pasture-lambing system. Lambs were born to Barbados Blackbelly (BB) or St. Croix dams (SC) mated within breed (purebred) or to Dorset (terminal) in single sire mating groups. Lambs were born in April (2013 and 2015), December (2013 and 2015), and August (2014 and 2016) and weaned at 9 weeks of age. Traits considered were BW at birth (BW0; n = 959), 65-d adjusted weaning BW (BW65; n = 788), and survival to weaning (n = 959). Data were analyzed with fixed effects of dam age, sex, birth type, dam breed (BB vs SC), dam mating system (purebred vs terminal), birth month-year, and significant two-way interactions and a random dam effect. Dam breed did not impact BW65 (P = 0.09). While BW0 was greater for lambs born to SC than BB dams (3.44 vs 3.23 kg; P &amp;lt; 0.01), survival to weaning was greater for lambs born to BB than SC dams (0.93 vs. 0.87; P = 0.02). The dam mating system x birth month-year interaction was significant for both BW traits (P ≤ 0.01). Within birth month-year, BW0 was 18 to 24% greater and BW65 was 12 to 24% greater for terminal than purebred lambs (P &amp;lt; 0.01). However, BW0 differences between dam mating systems were greatest for August born lambs whereas BW65 differences were greatest for April born lambs. Lamb survival was not affected by dam mating system or birth month-year (P ≥ 0.27). Using a terminal sire improved BW without affecting survival of lambs reared by landrace hair sheep dams, making this a viable management tool to increase productivity of forage-based production systems.

Prediction of Myostatin on Carcass Composition in Crossbred Lambs

Abstract In order to maintain consumer acceptance of lamb meat, producers are aiming to produce leaner lambs through breeding for certain carcass characteristics. The Texel breed is known for its superior muscling phenotype due to a myostatin mutation. Because of this mutation, Texel and Texel cross lambs have been shown to have improved carcass lean with less fat in various locations throughout the carcass. The objective of this study was to observe the impacts of different sire and dam breeds on carcass composition. Lambs (n = 41) were produced by mating two dam breeds (Southdown or Suffolk) and two sire breeds (Southdown or Texel). Lambs were harvested and a hot carcass weight was obtained. At 24 h postmortem, a chilled carcass weight was taken, and each carcass was split in half. The left side of the carcass was cut into the four primal cuts and scanned using a DXA. The right half was used for standard carcass variables. After DXA scans, each primal was weighed and the major muscles were dissected from the primal cuts and weighed. Subsamples of muscles were used for total lipid analysis and Warner-Bratzler Shear Force testing. DXA scans showed a difference in the primal cut mass (P = 0.0207) with the Suffolk-Texel cross having the highest average primal cut mass at 12.52 kg. Southdown-Southdown lambs had the highest fat percentage (dam P = 0.0398; sire P = 0.0116). Dam breed had a more significant effect on muscle toughness (P &amp;lt; 0.0035). Southdown sired lambs had a higher SFA (P = 0.0046) and MUFA (P &amp;lt; .0001) but Texel sired lambs had a higher overall fatty acid ratio (P &amp;lt; .0001). On average, the Suffolk-Texel cross was shown to have heavier average weight for the primal cuts in the rack and leg, which are where some of the more profitable cuts of meat are located.